The subject matter disclosed herein relates to appliances using a mechanical refrigeration cycle, and more particularly to heat pump dryers and the like.
Clothes dryers have typically used electric resistance heaters or gas burners to warm air to be used for drying clothes. These dryers typically work on an open cycle, wherein the air that has passed through the drum and absorbed moisture from the clothes is exhausted to ambient. More recently, there has been interest in heat pump dryers operating on a closed cycle, wherein the air that has passed through the drum and absorbed moisture from the clothes is dried, re-heated, and re-used.
In a clothes dryer, it is desirable to know when the clothes have achieved a desired level of dryness, so that the dyer can be shut down. Current systems rely on a capacitance reading between two electrodes, known as dry rods. Such systems typically stop producing a usable signal before the point when the clothes are completely dry, so that some approximation is necessary to anticipate when the clothes will actually be dry.